Many child resistant containers for dangerous and potentially harmful materials such as drugs, household chemicals, and the like, have consisted of containers and caps therefor which have cooperating locking means to make them difficult of opening by a child of tender years.
The neck finishes of many of these devices have one or more radially extending abutments or stops on their outer sides, usually adjacent the bases of their necks and the caps usable therewith have depending or inwardly extending lug or lugs which cooperate with the stop or stops after the caps have been screwed onto the containers to closed position to make it difficult for a child to unscrew the caps off of the containers. In these combinations the abutment faces of the stops on the containers lie in radial planes.
A cap for such a combination has a skirt-like portion which is flexible so that it may be squeezed along a diametric line which extends at least generally at right angles to the diametric line of the lug or lugs. This flares the flexible portion outwardly beyond the stop or stops and allowing retrograde rotation of the cap relative to the container.
Child resistant containers and closures therefor are illustrated, for examples, in Gach et al U.S. Pat. No. 3,888,373 and in Mumford U.S. Pat. No. 4,134,513 as well as in many other patents in this art.
Long usage of child resistant combinations such as those being discussed has revealed that frequent opening and closing of the containers, i.e., repeated engagement of the cap lugs with the abutment faces of the container stops, tends to wear away the container stops so that, eventually, mere rotation of the caps in a retrograde direction will cause the cap lugs to be cammed outwardly and thus slid past the container stops rather than being positively engaged therewith to prevent rotation of the caps beyond the child resistant position.
It is, therefore, the principle object of the instant invention to provide container stops which are so designed as to increase the child resistant force upon engagement of the cap lugs with the container stops and to inhibit, if not prevent, the wearing of the container stops in the manner encountered according to the arrangements of the prior art.
In my earlier application Ser. No. 966,946 referred to above now U.S. Pat. No. 4,172,533, I have shown one embodiment of child resistant locking means according to the invention in which the abutment faces of the container stops lie in planes which are parallel to the axis of the neck but not radial and which are inclined backwardly to intersect the exterior of the circular surface of the container at angles of less than 90 degrees to tangents to that surface at the lines of intersection therewith.
The present application discloses the improved stop construction as embodied in other types of cap structures.